Lamp socket for tubular lamps having contact pins at their ends



April 12, 1949. N. DECKER 2,457,256

LAMP SOCKET FOR TUBULAR LAMPS HAVING CONTACT PINS AT THEIR ENDS 'Filed Sept. 10, 1945 I .32 /6 A /733 5/ 5 :53 2M! L 33 35 -3 5 m p v 38 WW fi lll'l 60 ll 0 \26 I INVENTOR J5 Mb/golaa De ATTORNEY Patented Apr. 12, 1949 UNITED STATES PATENT OFFICE LAMP SOCKET FOR TUBULAR LAMPS HAV- ING CONTACT PINS AT THEIR ENDS This invention relates to sockets for the reception of the contact-making prongs or pins of fluorescent lamps and particularly to the means for guiding said prongs into the operative or contact-making positions thereof and for removably locking the prongs in such positions.

While the base prongs of fluorescent lamps are substantially standardized and identical, the cooperating sockets for the reception of the prongs are not, such sockets taking any one of a variety of different forms depending largely on the means employed for guiding the prongs into proper electrical contact with the conductors or contactmaking members of the socket.

In most cases, however, the sockets are spaced apart a selected fixed distance depending on the length of the lamp so that the guiding means requires the insertion of both of the prongs at one end of a comparatively long lamp into slots or openings in the adjacent socket, the insertion of those prongs at the other end of the lamp into similar slots or openings in the opposite socket, and finally the use of a rotary movement of the lamp through a greater or smaller angle to make the required contact. Those unfamiliar with the peculiarities of the particular sockets into which they may be attempting to insert the lamp prongs for the first time, or unskilled persons, are quite likely to and frequently do become confused by the number, sequence and exact amounts of the successive movements needed to complete the inserting operation properly, and may start the rotary movement prematurely, thereby putting excessive stress on the prongs which said prongs are not designed to withstand, with consequent bending or other damage thereto, or so jamming the parts that the inserting movement of the lamp vcannot be completed, the lamp cannot be withdrawn, and the services of an expert or repair or replacement become necessary.

In many of those sockets heretofore known which provide substantially adequate guiding means for the prongs, such means may be comparatively intricate or expensive, or requires the use of additional parts, or else the means for locking the prongs is inadequate, or if eifective to perform its locking function, may require the employment of excessive force upon the prongs to carry the prongs into their locking positions, with the consequent serious danger of breaking or so bending the prongs as to render the lamp useless.

My invention therefore contemplates the provision of a socket provided with guiding slots or grooves defined by guide walls so shaped and arranged that after both prongs at one end of the lamp have been placed in the grooves therefor in one socket in the most obvious manner, the prongs at the other end of the lamp can only be correctly inserted into the corresponding grooves or slots of the other socket, and thereafter premature rotational movement of the lamp cannot create any undue stress on the prongs sufiicient to damage them, but instead, such movement is automatically converted into movement in the proper direction to complete the locking of th prongs in place in the socket.

The invention further contemplates the provision of a socket having such guides for the lamp prongs that regardless of how or where the prongs at one end of the lamp may be inserted initially into the adjacent socket, the prongs at the other end of the lamp may equally well be inserted into the socket therefor, and thereafter a minimum force exerted in any one of a number of different directions in a wide range erroneously or deliberately, is eifective to advance the prongs to the proper locked positions thereof thereby to avoid danger of damage resulting from assembly of the parts by unskilled or careless persons.

The invention further contemplates the provision of a socket having means for apprising the user when a change in the direction of the initial movement of the lamp is advisable during the inserting or withdrawing operation thereof, so that such change may be made if desired to facilitate the operation.

The invention further contemplates the provision of a simple and inexpensive socket having a minimum number of parts but provided with guide walls for the lamp prongs shaped and proportioned to prevent the necessity for exerting undue locking force thereon by preventing any possibility of simultaneous locking of both prongs with the socket contact members and requiring each of the prongs to be locked in place separately.

The invention further contemplates such relative arrangement of the socket contact members and the socket guide walls that when the lamp is inserted into its sockets in a natural and obvious manner, the lamp prongs are locked adequately by the contact members on the exertion of a minimum amount of force on the relatively delicate lamp prongs.

The various objects of the invention will be clear from the description which follows and from the drawings, in which Fig. 1 is a foreshortened front elevational view of a typical lamp and socket installation.

Fig. 2 is a side elevation of one face of a typical socket showing the lamp prongs in cross section and locked in place.

Fig. 3 is a vertical section of the socket taken on the line 33 of Fig. 2.

Fig. 4 is a side elevation of the opposite face of the socket from that shown in Fig. 2, with the cover plate partly broken away to show the interior structure.

Fig. 5 is a horizontal section of the socket taken on the line 55 of Fi 2.

Fig. 6 is an enlarged fragmentary elevational View of the socket showing a modified form "of the bottom slot.

Fig. '7 is an enlarged fragmentary elevational view of a slightly modified form of the socket showing the guide slots and guide walls for guiding the prongs into the indicated locked positions thereof.

For the purpose of clarity in what follows and in the claims, the line 3-3 of Fig. 2 will be referred to as the vertical center line of the socket, and lines parallel to the line 5-5 will be termed horizontal, though it will be understood that the socket may be mounted in any convenient position, angular or reversed from the position shown.

In the practical embodiment of the invention shown by way of example, the socket in is provided with a substantially triangular recess in the inner face 22 thereof, said recess being partitioned to form the guide slots H, l2, l3, l4 and I5 best seen in Fig. 2 and peculiarly shaped, arranged and proportioned as will be more fully described hereinafter. The slot i2 is separated or partitioned from the slots l3 and M by the outstanding projections 16 and I! respectively,

the Walls of the slots and projections serving as the means to guide and to assist in directing the prongs l8, 19 of the lamp 20 into place. Said prongs are of the usual type, that is, in the form of longitudinally projecting cylindrical pins, a pair of each being provided at each end of the lamp so that the lamp may be turned end for end or either end inserted into either socket IU of Fig. 1. The prongs of each pair are identical and diametrically opposite each other and equidistantly spaced from the axis of the lamp.

The sockets ID are installed in a fixture or reflector 2| with the corresponding inner faces 22 thereof facing each other whereby the prongs of a long lamp may be inserted into the sockets in much the same manner as a common and well known window shade roller is inserted into its perforated and slotted supports. That is, the prongs at one end of the lamp are first inserted into any parts of the slots of one socket and then the prongs at the other end are inserted into the other socket by sliding the prongs through the slot II. It will be understood, however, that in a short and easily manipulated lamp, the prongs at both ends of the lamp may be inserted into both sockets at the same time. The vertical center line 33 of the slot l I being perpendicular to the horizontal line joining the centers of the prongs in the locked positions of the prongs, it is obvious that the lamp must be turned in some manner to complete the inserting operation. The improper initiation of the turning movement for whatever reason is a frequent cause of the difficulties hereinbefore mentioned which have been experienced with sockets heretofore known.

In order to clarify the guiding action of the slots and their walls, a brief description of the general socket structure appears desirable. The main socket member 23 is designed to be economically molded in one piece of suitable plastic insulating material and has a peripheral wall or flange 24 outstanding from the face 22 to provide a space within the socket for the reception of the sheet spring contact members 25 and 26 and their supporting parts as well as for the current carrying leads and terminals as 21 and '23. The cover 29 is removably secured to the member 23 inside of the flange 24 and constitutes the outer face of the socket. At its upper end as shown in Figs. 2, 4 and 7, each of the contact members 25 and 26 has an outwardly bent part 30 forming a locking hump in the member, said part 30 projecting across the slot l3 or I 4 so as normally to obstruct entrance of the prongs into the slot except either from above or in a horizontal direction. Below the bent part 30 is the outwardly convex and inwardly concave locking part or bend 3'! fitted to and adapted to receive one of the lamp prongs therein and to press the prong against the lower wall of the slot [5 when the prong is in proper electrical contact with its contact member thereby adequately to lock the prong in place. The contact members are biased inwardly but yield outwardly under the downward pressure of the pron-g upon the part 30 or upon substantial upward or horizontal pressure upon the part 3|, but the weight of the lamp and other usual forces such as vibration or the like are insuificient to exert enough force to effect such yielding whereby the contact members are effective to perform their locking functions until deliberate lamp-withdrawing forces are exerted on the prongs.

Extending outwardly from the inner face 22 is the narrow upright central wall 32 closing or forming a back on the central outer part of the generally triangular recess or opening 33 in the face 22, said wall 32 carrying the projections l1 and IE on its inner face. The upright edges of the wall 32 are substantially straight and flat and are spaced a distance apart less than the greatest overall width of the projections l6 and I! whereby the lower widened parts of said projections remote from each other overhang the side edges of the wall 32 and project into the remaining unbacked or unobstructed part of the opening 33. The upper ends of the contact members move in said otherwise unobstructed part outwardly of the face 22 when pressure thereon is applied or released, said members being of sufficient width to make adequate contact with and to lock the prongs inserted into the guide slots as shown in Fig. 5.

The socket 1'0 being substantially symmetrical about its vertical center line, a detailed description of one half thereof will suffice for both halves particularly in so far as the slots thereof are concerned. To attain the purposes of the invention, the walls 34 and 35 bounding the slot [3 are arcuate and center about the opposite locking point of the prong which corresponds to the center of the opposite bend 3| when said bend is operative to lock the prong. The lower wall 36 and the upper wall 31 bounding the slot I5 are horizontal and are arranged equal distances from the line joining the opposed locking points. A concave fillet as 38 connects the walls 36 and 34. In the form shown in Fig. 2, the walls 39 and 40 of the slots H and I2 are substantially vertical but discontinuous and in alignment with each other, except that the uppermost part of the wall 39 is convex and flared to permit easy entrance of the prong into the slot II. A suitable convex fillet joins th walls 39 and 34. All of the slots are made appreciably wider than the diameters of the prongs for the purpose later to be explained.

It will be noted that the walls 35, 31 and 39 of i the respective slots I3, I5 and I2 form the edges or walls of the generally triangular projection I6, said walls being joined by rounded corners to permit the prongs moving in said slots easily to change their direction of movement from one slot to the other at the intersections or iunctures thereof. It will also be noted that the various slots partitioned out of the recess form substantially an equilateral triangle having arcuate sides and a straight horizontal bottom and bisected by an upright slot extending past the upper ends of the arcuate side slots.

The most obvious and natural movement for inserting the prongs into the socket is also the one requiring the least efiort and the one least likely to cause damage to the prongs, but the socket is also adapted for practically any movement which a user might fancy or adopt inadvertently or in mistaken judgment. In manipulating a comparatively long lamp, the user would naturally tilt the lamp slightly out of the horizontal and insert the prongs at one end of the lamp through the slots II' and I2 by a vertically downward movement until the lower prong touches the bottom wall 36 of the slot I5. He would then lower the other end of the lamp and similarly insert the prongs at said other end into the slots II and 12 of the adjacent socket until the lower prong touches the bottom wall of the slot I5 thereby apprising' him that a change in the direction of movement is desirable. Insertion of the prongs at said one end of the lamp orients the lamp to bring both sets of prongs into vertical alignment or nearly so, thereby making similar insertion of the prongs into the other socket easy and quick. Of course, in a short lamp, both sets of prongs may be simultaneously inserted into their respective sockets. With the lower prongs in the positions mentioned, the upper prongs are arranged between the fillets below the upper end of the slot I I. Now the lamp obviously is to be rotated to carry the prongs into contact-making and locked position. Such rotation is either in a clockwise or in a counterclockwise direction and moves the lower prong (as I8) along the straight wall 36 toward one contact member (as 25) and at the same time moves the other prong (as I9) along the slot I4 (or I3 as the case may be) until said other prong I9 reaches the upper part 30' of the contact member 26, where a sufficient resistance to further rotation is encountered temporarily to halt the prong I9 and to cause completion of the horizontal movement of the lower prong I8 into the concave bend 3|, flexing the contact member slightly and enough to lock the prong I8 in place. When the resistance of the locking contact member 25 to further flexing is greater than that offered by the other contact member 26, said other prong I 9 by its cam action on the part 30 causes the contact member 26 to flex away from the prong thereby allowing the prong I9 to snap into the bend 3| of the member 26 to complete the locking operation.

It will be noted that the movements just described do not put any excessive stress upon the prongs and are the movements naturally performed during the assembly of devices of this character and that only one contact member at a time is flexed during the operation, the prong I8 merely sliding into place without material movement or flexing of the member 25.

Assuming that the operator does not proceed as above, the danger of damage is nevertheless minimized. For example, if instead of sliding the prongs at one end of the lamp through the slots H and I2, let ill. be assumed that the operator attempts to stick the prongs into the slots of one socket by a substantially horizontal or thrusting movement. The lower prong cannot enter either of the lower corners of the slots adjacent the fillets 38 nor the lower parts of the slots I3 or I4 should the operator attempt to insert it at any of those places, because of the obstructing action of the contact members. Let us now suppose that the operator, realizing this after his first failure, moves the prongs somewhat higher and inserts the prong I8 into the slot I3 above the member 25. The other prong I9 then enters the slot I'I near its top. The lamp is consequently in a slight- 1y twisted position, that is, the prongs are considerably out of vertical alignment and the lamp is also inclined upwardly toward the other socket. However, the lower prong I8 at the higher end of the lamp may nevertheless be readily passed through the slot II and into the slot I3 of its adjacent socket by lowering said end, such movement being in a non-vertical or slightly inclined direction and being possible by reason of the play of the prongs transversely within the wider slots. The downward movement of the prongs in said other socket is halted by the contact member and the operator is apprised by such halting that some movement other than downward movement is advisable. If, the operator persists in forcing a downward movement of the lamp, the prong I8 merely flexes the member 25 and slips into locked position while the other prong I9 enters the slot I3 and begins to move downwardly therein in a rotary movement produced by the camming action of the wall of the slot, and which movement the operator naturally assists, to complete the locking of the prong I9 in the contact member 26.

On the other hand, should the operator change to a rotary movement instead of a downward movement, the same locking movement occurs, since the prong I9 slides along the wall of the slot II and causes the prong I8 to drop into place, the prong I9 then moving along the slot I4 into looking position.

Assuming that the operator begins by inserting the prong I8 at one end of the lamp somewhere in the slot I5 to one side of the slot I2 and by inserting the prong I9 into the lower part of the slot II, when he attempts to pass the prongs at the other end of the lamp into the slot II, theprong I8 at said other end of the lamp by engaging the convex upper end part of said slot I I and then being guided thereby into the straight part of the slot II, tends to become aligned with the corresponding prong I8 at said one end of the lamp owing to the resulting rotation of the lamp toward a vertically aligned position of the prongs I8 and I9 at said one end of thelamp. Or else one prong may enter an arcuate slot I3 or I4 after which rotation of the lamp completes the locking operation in the manner above described.

To still further minimize any possibility of injuring or breaking the prongs during any type of inserting movement, the slots may be still further widened and shaped at selected points as shown in Fig. 7. In that form of the invention, the entrance slot II is replaced by the slot 50, the width of which at its narrowest point is about twice the diameter of the prong, and at its top enemas about three or four times said diameter. The convex walls of said slot 5B diverge upwardly from the narrowest part of the slot to permit easy passage of both prongs therethrough when the prongs are out of vertical alignment, and to permit easy rotation of the lamp when one prong is initially inserted into the slot l3 or 14 above the contact member.

Should the lower prong be inserted between the projections 52 and 53 of one socket with each set of the lamp prongs aligned along an inclined line and out of the vertical, the downwardly diverging walls 54 and 55 of said projections make it possible to insert the other set of prongs into the other socket by an inclined movement with out straining the prongs. Premature rotation of the lamp in either direction prior to the completion of the inserting movement of the prongs to the lowest parts of the respective slots, is automatically converted into movement toward the locking positions of the pron-gs by the camming action of the walls of the slots in a manner which will now be obvious, particularly in view of the convex corners on the projections and on the entrance slots, the arcuate slot walls, the straight bottom slot, and in the form of Fig. 7, the divergent adjacent walls of the projections.v It will also here be noted that a continuation of the wall 54 or 55 falls between or inside of the walls 51 of the slot 50.

The upwardly tapered and rounded projection 56 upstanding from the bottom wall 51 of the horizontal slot 58 of Fig. '7 serves to start the rotation of the lamp automatically on the initial inserting movement of the prongs into the sockets, and apprises the operator when and in what direction to rotate the lamp to lock the prongs in place. In other Words, when the prongs are first passed through the slots 50 and 58, the lowermost prong touches and slides transversely ed the projection 55 to one side of said projection thereby slightly rotating the lamp. Such rotation is felt by the operator who now need merely continue the indicated rotation. Should he disregard the notice thus given and continue downward pressure, the lower prong will nevertheless slide along the wall 51 toward the contact member. Should he rotate the lamp in the direction opposite to that indicated, the lower prong will merely ride over the projection whereafter the prongs continue to move toward the contact members.

In that form of the invention shown in Fig. 6, the generally triangular recess in the face 22 of the socket is provided with various slots substantially identical with those shown in the socket of Fig. 2, and is also provided with the substantially triangular projection 60 somewhat similar to the projection 56 of Fig. '7. Said projection 60 is arranged at the mid-point of the lower edge 36 of the horizontal slot [5. The sides 61 of the projection 6|] are made concave in this form of the invention to meet at the substantially sharp edge or vertex 62 and are preferably concentric with the rounded corners 31. The operations of inserting and withdrawing the prongs from the sockets are substantially as explained in connection with Fig. 2. However, when one pron-g passes downwardly through the slots H and I2 into contact with the projection 60 during an inserting operation, it slides off the projection to one side or the other thereof and makes an audible click, thereby apprising the operator by sound and feel that rotation of the lamp should be started.

Similarly, during the withdrawing operation, the prong sliding along the horizontal groove l5 toward the middle of the groove strikes a concave side SI of the projection 60 to make a clicking sound and at the same time rises slightly into the slot l2, thereby apprising the operator that the prong may then be drawn straight out of the upright slot [2.

In all of the forms of the invention, continued rotation of the lamp after the prongs are in their respective locking positions, causes no damage to the parts and may be kept up indefinitely, but the audible successive clicking sounds made by the snapping of the prongs into the bends of the spring contact members gives notice when rotation of the lamp should be stopped. An audible signal is given as well as 'aslight stoppage followed by a change of movement which is felt by the operator to apprise him when he should change the movement originally given to the lamp.

It will be seen from the above that regardless of the manner of inserting the prongs into the socket slots and of the point in the movement of the prongs when rotation of the lamp is begun, movement of the prongs toward their locking positions is assured in all cases which can reasonably be anticipated, whereby the excessive stresses on the prongs and the damage so frequent heretofore is avoided.

While certain specific forms of the invention have been illustrated and described, various changes may be made therein without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. In a socket for a fluorescent lamp provided with spaced contact prongs at each end thereof, a pai of spring contact members each having a bend therein to receive and lock one of the prongs, and means on the socket for guiding the prongs into locked contact with the bend and the socket, said means comprising a first pair of radially spaced arcuate walls extending partway through the thickness of the socket and bounding an arouate slot therebetween and leading toward one of the bends, a second similar pair of arcuate radially spaced Walls diverging downwardly from the tops of the first pair of walls and leading toward the other of the bends, said arcuate walls termihating below said bends a distance sufficient to permit said members to press prongs arranged in the bends against the fillet hereinafter mentioned, a pair of vertically spaced horizontal walls extending between the lower ends of said pairs of arcuate walls and arranged with the line midway therebetween coincident with the line joining the centers of said bends, a concave fillet joining each end of the lower of said horizontal walls to the adjacent arcuate wall, and a pair of horizontally spaced substantially vertical walls extending upwardly past the arcuate walls to the edge of the socket and extending downwardly to the upper oi the horizontal walls, each of said pairs of walls bounding a slot therebetween of sufilcient depth and width to permit the insertion and movement of a prong therein, said walls exerting a camming action on the prongs to guide said prongs toward the bends on the exertion of force on the lamp in any direction having a downward component after the prongs have been moved into engagement with any of the walls.

2. In a socket for a lamp provided with spaced contact prongs, correspondingly spaced yieldable contact members each having a contact-making and prong locking bend therein in proximity to the upper end thereof, there being three guide slots in the socket to guide the prongs inserted into any two of the slots toward the bends, said slots being arranged in the general form of an equilateral triangle with one side horizontal and the other sides arcuate about the respective opposite vertices as centers, there being a fourth slot perpendicular to and intersecting the horizontal slot and extending upwardly past the upper vertex of the triangle, and a pair of similar outstanding projections on the socket arranged respectively on opposite sides of said fourth slot and forming the inner walls of said three guide slots and preventing communication between the slots except at the ends of the respective slots.

3. In a socket for a lamp having spaced contact-making prongs, a pair of similar prongguidin projections outstanding from the wall of a generally triangular recess in a face of the socket and arranged symmetrically about and in transverse spaced relation to the vertical center line of the socket to form guide slots between the projections and the adjacent walls of the recess and to form an upright slot between the projections, the bottom wall of the recess between the arcuate walls hereinafter mentioned and the upright slot lying in a horizontal plane and the adjacent bottom walls of the projections being convex thereby partitioning an interrupted horizontal slot from the recess, the outer side walls of the recess and of the projections adjacent thereto being arcuate about the opposite ends respectively of the horizontal slot to divide the recess further into symmetrical arcuate slots leading to the respective ends of the horizontal slot and merging at the tops thereof into a vertical slot extending to the upper edge of the socket and aligned with the upright slot and above and wider than said upright slot, the corresponding inner walls of the projections diverging downwardly to widen the upright slot at the lower part thereof, the straight continuation upwardly of said inner walls of the projections falling between the walls of the vertical slot, whereby the respective prongs inserted into any of the slots are moved toward the respective ends of the horizontal slot when the lamp is rotated after such insertion or when the lamp is pressed in a generally downward direction after such insertion and then rotated.

4. In a socket for a lamp provided with a pair of spaced contact prongs at each end thereof, a pair of transversely separated and generally triangular projections each widest at the lower edge thereof, said lower edge being horizontal, said projections being arranged symmetrically about the vertical center line of the socket and in a recess in the socket and partitioning from the recess the upper edge of a horizontal slot, the inner edge of each of a pair of arcuate slots and the edges of a generally upright slot, said widest lower edges of the projections constituting said upper edge of the horizontal slot, there being a vertical slot in the socket extending from the upper edge of the socket to the top of the upright slot and communicating with the arcuate slots and with the upright slot, the lower edge of the horizontal slot having a generally triangular projection upstanding from the middle point thereof in the path of a prong passed downwardly through said upright slot to divert said prong to one side of said middle point and to divert a prong passing along the horizontal slot upwardly thereby to apprise the person inserting the lamp into the socket or withdrawing the lamp from the socket that a change in the direction of movement of the prong is desirable,

said upstanding projection extending partway across the horizontal slot and having the uppermost point thereof in sufficient downward spaced relation to the lowermost points of the first mentioned projections to permit the prong to pass between the upstanding projection and the first mentioned projections from the upright slot into the horizontal slot and from the horizontal slot into the upright slot.

5. In a socket for a lamp provided with a pair of spaced prongs at each end of the lamp, a pair of similar prong-guidin projections each having its greatest width at its lower part and each tapering upwardly to a narrower width, the projections bein arranged symmetrically about the center line of the socket and being spaced transversely apart, there being an upright slot between the projections of sufficient width to receive the prongs therein, said upright slot extending to the edge of the socket, there being a triangular slot around the outer side edges and the bottom edges of the projections, the side portions of the triangular slot being arcuate and the bottom portion of the triangular slot being straight and horizontal and extending between and communicating with the lower ends of the arcuate slots and communicating with the upright slot and having a horizontal uninterrupted plane lower surface.

6. A socket according to claim 3 wherein the bottom wall of the recess is provided with an upstanding tapered projection arranged in alignment with the upright slot and of not greater width than the width of the upright slot and of lesser height than the height of the horizontal slot.

7 In a socket for a lamp provided with spaced contact prongs, said socket being adapted to lock the prongs and to make electrical contact there'- 4 with at a pair of predetermined spaced and horizontally aligned points of the socket, a plurality of pairs of guide walls in the socket guiding the prongs of the lamp toward said points respectively, and contact-making means for locking the prongs at said points, each wall of each pair of walls being in spaced relation to the other wall of said pair of walls and bounding a slot therebetween whereby the plurality of pairs of guide walls bound a plurality of slots, one of said slots being horizontal and extending between the locking points, a second of said slots being arcuate about one of the locking points as a center, a third of said slots bein arcuate about the other locking point as a center and a fourth of said slots being vertical and extending upwardly from the horizontal slot to the upper edge of the socket, said walls serving as fixed cams to convert motion of the respective prongs in any direction having a downward component into movement toward the respective locking points after the prongs have been inserted into any two of the slots, the lower wall of the horizontal slot having a smooth, continuous and uninterrupted plane surface, the lengths and widths of the slots being substantially equal and bein suitably proportioned to effect the aforesaid movement of the prongs.

8. In a socket for a lamp provided with spaced prongs, spaced yieldable contact members each provided With a prong-locking bend, said socket having a generally triangular recess in a face thereof defined by three prong-guiding walls on the socket surrounding the recess except at the top of the recess where the recess extends to the edge of the socket, a pair of guide projections arranged in the recess symmetrically about the vertical center line of the socket and in transverse spaced relation to each other and also in inward- 1y spaced relation to the walls of the recess, the two side walls of the recess being arcuate about the center of the bend of the opposite contact member as a center, the bottom wall of the recess except at its mid-portion being a horizontal plane surface extending between the arcuate side Walls of the recess, and an upwardly tapered projection having concave edges upstanding from the mid-portion of said bottom wall and terminating at an uppermost point in sufficient downward spaced relation to the projections to permit the passage of the lamp prongs therepast, and midway between the projections.

9. In a socket for a lamp provided with spaced contact prongs, correspondingly spaced yieldable contact members each having a contact-making and prong locking bend therein in proximity to the upper end thereof, there being three guide slots in the socket to guide the prongs inserted into any two of the slots toward the bends, said slots being arranged in the general form of anequilateral triangle with one side horizontal and the other sides arcuate about the respective opposite vertices as centers, there being a fourth 12 slot perpendicular to and intersecting the horizontal slot and extending upwardly past the upper vertex-of the triangle, a pair or similar outstanding projections on the socket arranged respectively on opposite sides of said fourth slot and forming the inner walls of said three guide slots and preventing communication between the slots except at the ends of the respective slots, and an upstanding projection at the mid-point of the lower wall of the horizontal slot, said upstanding projection being of lesser height than that of the horizontal slot.

NICHOLAS DECKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,560 De Reamer Oct. 31, 1944 2,257,786 Chirelstein Oct. 7, 1941 2,259,096 Alden Oct. 14-, 1941 2,279,913 Cavanagh Apr. 14, 1942 2292,05} Chi'relstein Aug. 4, 1942 22971138 Beal Oct. 6, 1942 

